Existing rotation counters typically have a moving part that is clamped or fixed to a rotating shaft and a stationary part that is attached to or positioned in tandem with a non-rotating structure. A rotation sensor or rotary encoder is coupled between the two parts to count the number of turns of the moving part relative to the stationary part.
Some devices use a pendulum or weight to form the non-rotating part that stays in a downward position under gravity. For example, a hubometer is a well-known device that is mounted on the axle of a trailer or other towed vehicle for measuring the number of revolutions of the axle for conversion into a measure of distance traveled by the vehicle. The moving part of the device rotates with the axle or wheel relative to an eccentrically mounted weight on an internal shaft that remains pointing downwards as the rotating part of the hubometer rotates round it.
Other types of revolution counters have blind sensors that are designed to count the revolutions of a shaft or gear that is coupled to the driven part. One disadvantage with these prior types of devices is that the moving and/or stationary parts must be designed specifically to attach to the rotating structures the devices are used to measure.
In industrial applications, it is often desired to accurately count the number of turns (and fractional increments thereof) that a driven part is turned for adjustment to a target or optimal position. For example, in the aircraft industry, airplane wings commonly use telescopic plane surfaces to temporary increase wing surface and curvature during take-off and landing phases, and to increase lift effect at low speed. Both leading and trailing edges are equipped with extendable/retractable ancillary wing surfaces which are actuated by a single rotary motor connected to a chain of jack-screws linked/synchronized together by torque tubes. To insure mechanical axial compliance during wing flex or under ambient temperature variation, each torque tube for adjacent gearboxes is connected through a splined shaft. The synchronization of each gearbox to insure a true parallel movement of leading and trailing edges of the wing's main beam is dependent on an exact angular indexing of each gearbox input splined shaft. Initial installation as well as periodic maintenance task may require a temporary disconnection of one or more of these synchronization torque tubes in order to manually move one or more of these leading/trailing edge sections. If the control surfaces are run too far either in or out, the range of motion of the control surfaces during operational use may result in mechanical stops that can cause damage to the gearbox, resulting in the need to remove or repair the gearbox.
It is therefore desired to provide a revolution counter tool that can keep precise count of the number of turns/increments of angular indexing of a gearbox or motor-driven part so that it can always be returned to its optimal position during installation or repair, and even by a different mechanic. It is also desirable that the revolution counter tool be usable with different types of driven parts and different types of driving or turning parts, so that a special tool does not need to be designed individually for use with each type of application. As angular indexing movements may be made in either rotational direction, it is also important that the tool be bi-directional.